/* 基础样式重置 */
* {
  box-sizing: border-box;
}

/* 搜索框容器样式 */
.search-container {
  margin-bottom: 30px;
  padding: 20px 0;
}

/* 搜索框样式 */
.search-box {
  display: flex;
  max-width: 500px;
  border: 2px solid var(--border-color);
  border-radius: 5px;
  overflow: hidden;
  background: var(--bg-color);
  box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
}

.search-input {
  flex: 1;
  padding: 12px 16px;
  border: none;
  outline: none;
  font-size: 14px;
  color: var(--text-color);
  background: transparent;
}

.search-input::placeholder {
  color: var(--text-light);
  font-size: 14px;
}

.search-btn {
  padding: 12px 20px;
  background: var(--danger-color);
  color: var(--text-white);
  border: none;
  cursor: pointer;
  font-size: 14px;
  font-weight: 500;
  display: flex;
  align-items: center;
  gap: 6px;
  transition: background-color 0.3s ease;
  border-radius: 0 5px 5px 0;
}

.search-btn:hover {
  background: var(--danger-hover);
}

.search-btn:disabled,
.search-btn.disabled {
  background-color: #ccc;
  color: var(--text-muted);
  cursor: not-allowed;
  opacity: 0.6;
}

.search-btn:disabled:hover,
.search-btn.disabled:hover {
  background-color: #ccc;
  transform: none;
}

.clear-btn {
  padding: 12px 16px;
  background: #f7fafc;
  color: var(--text-muted);
  border: none;
  cursor: pointer;
  font-size: 14px;
  display: flex;
  align-items: center;
  gap: 6px;
  transition: background-color 0.3s ease;
}

.clear-btn:hover {
  background: #edf2f7;
}

.clear-icon {
  font-size: 14px;
}

/* 筛选下拉菜单样式 */
.filter-dropdown {
  border-left: 1px solid var(--border-color);
  background: var(--bg-color);
}

.price-filter {
  padding: 12px 16px;
  border: none;
  outline: none;
  font-size: 14px;
  color: var(--text-color);
  background: transparent;
  cursor: pointer;
  min-width: 120px;
  appearance: none;
  background-image: url("data:image/svg+xml;charset=UTF-8,%3csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24' fill='none' stroke='currentColor' stroke-width='2' stroke-linecap='round' stroke-linejoin='round'%3e%3cpolyline points='6,9 12,15 18,9'%3e%3c/polyline%3e%3c/svg%3e");
  background-repeat: no-repeat;
  background-position: right 8px center;
  background-size: 16px;
  padding-right: 32px;
}

.price-filter:hover {
  background-color: #f8f9fa;
}

.price-filter:focus {
  background-color: #f8f9fa;
}

/* 下拉菜单选项样式 */
.price-filter option {
  padding: 8px 12px;
  font-size: 14px;
  color: var(--text-color);
  background: var(--bg-color);
}

.price-filter option:hover {
  background: var(--danger-color);
  color: var(--text-white);
}

/* 课程列表样式 */
.course-grid {
  display: flex;
  flex-wrap: wrap;
  gap: 20px;
  margin-bottom: 20px;
  justify-content: flex-start;
}

.course-item {
  background: var(--bg-color);
  border-radius: 8px;
  overflow: hidden;
  transition: transform 0.3s ease, box-shadow 0.3s ease;
  display: flex;
  flex-direction: column;
  height: 100%;
  position: relative;
  z-index: 1;
}

.course-item:hover {
  transform: translateY(-5px);
  box-shadow: 0 8px 25px rgba(0, 0, 0, 0.15);
  z-index: 2;
}

/* 课程缩略图样式 */
.course-thumbnail {
  height: 160px;
}

.course-thumbnail img {
  height: 100%;
}

/* 课程内容区域 */
.course-content {
  padding: 20px;
  flex: 1;
  display: flex;
  flex-direction: column;
}

.course-name {
  font-size: 16px;
  font-weight: 600;
  margin: 0 0 10px 0;
  color: var(--text-color);
  line-height: 1.4;
  display: -webkit-box;
  -webkit-line-clamp: 2;
  line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
  height: auto;
  min-height: 44px;
}

.course-description {
  font-size: 14px;
  color: var(--text-muted);
  margin: 0 0 15px 0;
  display: -webkit-box;
  -webkit-line-clamp: 3;
  line-clamp: 3;
  -webkit-box-orient: vertical;
  overflow: hidden;
  line-height: 1.5;
}

.course-metadata {
  margin-top: auto;
  display: flex;
  justify-content: flex-end;
  align-items: center;
  font-size: 12px;
  color: var(--text-muted);
}

.sidebar-title {
  font-size: 18px;
  font-weight: 600;
  margin: 0 0 20px 0;
  color: var(--text-color);
}

/* 课程链接样式 */
.course-link {
  flex: 0 0 calc(33.333% - 14px);
  min-width: 250px;
  text-decoration: none;
  color: inherit;
  display: block;
  transition: transform 0.2s ease;
}

.course-link:hover {
  text-decoration: none;
  color: inherit;
  transform: translateY(-2px);
}

.course-link:hover .course-item {
  box-shadow: 0 8px 25px rgba(0, 0, 0, 0.15);
}

/* 响应式布局 */
@media (max-width: 1200px) {
  .course-item {
    flex: 1 1 calc(33.333% - 13.333px);
  }
}

@media (max-width: 768px) {
  .course-item {
    flex: 1 1 calc(50% - 10px);
  }

  .search-box {
    max-width: 100%;
    margin: 0;
  }
}

@media (max-width: 576px) {
  .course-item {
    flex: 1 1 100%;
  }

  .search-box {
    flex-direction: column;
    border-radius: 15px;
    /* 移动端使用较小的圆角 */
  }

  .search-btn,
  .clear-btn {
    border-radius: 0 0 13px 13px;
    /* 移动端按钮圆角 */
  }
}